In prior replenishing systems, large tanks of developer and fixer were mixed, usually by hand, to provide the necessary replenishing solution or were filled with ready-to-use solutions from large containers. The use of large storage tanks of developer and fixer insured that there would be no shortage of solution when required. The mixing was both messy and subject to human error. Further, the storage space required by the large replenisher tanks was clearly objectionable. The odors generated by such large-volume stored solutions were also found to be annoying. Finally, this prior system required storage of ready-to-use solutions which lost their effectiveness with time.
One approach for eliminating the use of large replenisher tanks was the provision of smaller tanks to which component concentrate solutions of developer and fixer could be supplied when needed, together with the necessary water. Such a system, while an improvement over the use of pre-mixed, ready-to-use solutions nevertheless required hand addition of the component solutions into single entry openings. Thus, some degree of mess and odor still resulted and the erroneous introduction of the developer solution into the fixer portion and vice versa was stil quite possible.
Various systems of loading and introducing chemicals into tanks in an automatic or semi-automatic fashion are known. One such known system employs the automatic movement of knives to penetrate fixed containers in order to release the solution on demand. In this known arrangement, the movable knives are actuated by water pressure. Accordingly, when the water pressure is low, such system will fail to operate or, even worse, would not puncture all of the containers, resulting in a contaminated mixture.